Spatio-Temporal Heterogeneity of the Relationships Between PM(2.5) and Its Determinants: A Case Study of Chinese Cities in Winter of 2020

Fine particulate matter (PM(2.5)) poses threat to human health in China, particularly in winter. The pandemic of coronavirus disease 2019 (COVID-19) led to a series of strict control measures in Chinese cities, resulting in a short-term significant improvement in air quality. This is a perfect case to explore driving factors affecting the PM(2.5) distributions in Chinese cities, thus helping form better policies for future PM(2.5) mitigation. Based on panel data of 332 cities, we analyzed the function of natural and anthropogenic factors to PM(2.5) pollution by applying the geographically and temporally weighted regression (GTWR) model. We found that the PM(2.5) concentration of 84.3% of cities decreased after lockdown. Spatially, in the winter of 2020, cities with high PM(2.5) concentrations were mainly distributed in Northeast China, the North China Plain and the Tarim Basin. Higher temperature, wind speed and relative humidity were easier to promote haze pollution in northwest of the country, where enhanced surface pressure decreased PM(2.5) concentrations. Furthermore, the intensity of trip activities (ITAs) had a significant positive effect on PM(2.5) pollution in Northwest and Central China. The number of daily pollutant operating vents of key polluting enterprises in the industrial sector (VOI) in northern cities was positively correlated with the PM(2.5) concentration; inversely, the number of daily pollutant operating vents of key polluting enterprises in the power sector (VOP) imposed a negative effect on the PM(2.5) concentration in these regions. This work provides some implications for regional air quality improvement policies of Chinese cities in wintertime.